Fix some references

[interrobot]

Fixed a handful of references in the site:

1. https://mozorg.cdn.mozilla.net/tabzilla/tabzilla.js is returning an XML access denied response. I found the original file in wayback machine (Jan 2017) and moved it to local.
2. https://mozillalabs.com/ links are returning an SSL cert error (configured for *.github.com?). Secondarily, /en-US/ is returning a 404. I've altered the links to include "www" and removed "en-US" so that they still resolve.
3. The link to the IRC logs is dead. Could not find a replacement, and so I removed the link and contextual sentence.
4. The drawing jsfiddle is 404, I replaced the link with one from the wayback machine.